The subcellular and molecular aspects of the growth of Sindbis virus in animal cells in tissue culture will be studied. The sequence relatedness of the viral RNA species and identification of their templates, and the intramolecular location and mode of synthesis of homopolymer segments will be studied. The serological cross-reactivity of intracellular viral proteins will be characterized. By the use of acrylamide gel electrophoresis and metabolic inhibitors, the relation between processing of the precursor of the viral envelope protein and glycosylation of the protein will be investigated. The intracellular sites of synthesis, cleavage and glycosylation of the envelope protein, and the requirements for its insertion into plasma membrane will be studied. Finally, the physical and chemical characteristics of defective interfering particles of Sindbis, and the basis of their defectiveness will be studied.